| bone scan: falsely negative metastases | <radiology> Anaplastic tumours, reticulum cell sarcoma, renal cell carcinoma, thyroid carcinoma, histiocytosis, neuroblastoma, multiple myeloma (positive scan usually due to recent or impending fracture) (12 Dec 1998) |
|---|---|
| ventilators, negative-pressure | Body ventilators that assist ventilation by applying intermittent subatmospheric pressure around the thorax, abdomen, or airway and periodically expand the chest wall and inflate the lungs. They are relatively simple to operate and do not require tracheostomy. These devices include the tank ventilators ("iron lung"), portalung, pneumowrap, and chest cuirass ("tortoise shell"). (12 Dec 1998) |
| gram-negative | <microbiology> A common class of bacteria normally found in the gastrointestinal tract that can be responsible for disease in man (sepsis). Bacteria are considered to be gram-negative because of their characteristic staining properties under the microscope, where they either do not stain or are decolourised by alcohol during Gram's method of staining. This is a primary characteristic of bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide containing endotoxin. The gram staining characteristics of bacteria have resulted in an important classification system for the identification of bacteria. See: gram-positive (06 Oct 1997) |
| gram-negative aerobic bacteria | <microbiology> A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative aerobic rods and cocci | <microbiology> A group of gram-negative bacteria consisting of rod- and coccus-shaped cells. They are both aerobic (able to grow under an air atmosphere) and microaerophilic (grow better in low concentrations of oxygen) under nitrogen-fixing conditions but, when supplied with a source of fixed nitrogen, they grow as aerobes. (12 Dec 1998) |
| gram-negative anaerobic bacteria | <microbiology> A large group of anaerobic bacteria which show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative anaerobic cocci | <microbiology> A group of anaerobic coccoid bacteria that show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative anaerobic straight, curved, and helical rods | <microbiology> A group of anaerobic, rod-shaped bacteria that show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative bacteria | <microbiology> Bacteria which lose crystal violet stain but are stained pink when treated by gram's method. (12 Dec 1998) |
| gram-negative bacterial infections | <microbiology> Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative chemolithotrophic bacteria | <microbiology> A large group of bacteria including those which oxidise ammonia or nitrite, metabolise sulfur and sulfur compounds, or deposit iron and/or manganese oxides. (12 Dec 1998) |
| gram-negative facultatively anaerobic rods | <microbiology> A large group of facultatively anaerobic, rod-shaped bacteria that show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |
| gram-negative oxygenic photosynthetic bacteria | <microbiology> Widely distributed unicellular or multicellular bacteria. The cyanobacteria use chlorophyll a and phycobilins for oxygenic photosynthesis while genera in the prochlorales use both chlorophyll a and b but not phycobilins. (12 Dec 1998) |
| contingent negative variation | An increasing negative shift of the cortical electrical potentials associated with an anticipated response to an expected stimulus. It is an electrical event indicative of a state of readiness or expectancy. (12 Dec 1998) |
| positive-negative pressure breathing | Inflation of the lungs with positive pressure and deflation with negative pressure by an automatic ventilator. (05 Mar 2000) |